Sample
As detailed in the CONSORT diagram (Fig. 3), 1105 potential participants were screened. Of these, 485 were excluded for not meeting eligibility criteria. After enrollment, an additional 358 participants with unauthorized accounts (e.g., duplicate registrants) were withdrawn from the study and excluded from the analyses. An additional six unauthorized registrants completed study procedures and were subsequently removed from the analytic sample, given that they were initially missed as a result of a clerical error. Thus, the final sample included in analyses consisted of 256 participants. Of these 256 participants, 245 completed the Day 3 survey, 236 completed the Week 4 surveys, and 234 completed the Week 8 surveys.
CONSORT diagram. Although Day 3 and Week 4 survey data were collected as part of the parent study, they were not part of the analyses included in the present report.
Sample Characteristics
The analytic subsamples included 111 participants with elevated baseline levels of depressive symptoms and 107 participants with elevated baseline levels of anxiety symptoms at baseline as defined by a PHQ-8 score ≥ 10 and/or GAD-7 score ≥ 10, respectively. The sample size for the combined (elevated on PHQ-8 or GAD-7) groups comprised 139 participants. Some participants with elevated symptoms of both depressive and anxiety symptoms were in both analytic subsamples (n=79). Both the depressive symptom and anxiety symptom samples were predominantly female, educated, and employed, identified as non-Hispanic white and heterosexual, and had private health insurance (Table 1) with mean ages of 38 and 37 years, respectively. Among those with clinical levels of depressive symptoms, 50% had symptoms falling in the moderately severe or severe range (PHQ-8 score ≥ 15) and 49% reported concurrent mental health treatment during the study. Among those with clinical levels of anxiety symptoms, 44% had symptoms falling in the severe range (GAD-7 score ≥ 15) and 53% reported concurrent mental health treatment during the study.
The assessment completion rate at Week 8 was 91%. The PP population examined in sensitivity analyses comprised 177 (69%) of the 256 participants in the analytic sample after removing 67 (26%) who used WB-LIFE for at most 3 of 8 weeks and removing 22 (9%) whose EOS PHQ-8 and GAD-7 assessments at Week 8 were fully missing (no item scores were completed for each measure); the removals were not mutually exclusive. Sixty-four percent (N=71/111) of the elevated depressive symptoms subgroup met per protocol criteria and 59% (N=63/107) of the elevated anxiety symptoms subgroup met these criteria.
Table 1. Baseline sociodemographic and clinical characteristics, adherence, and satisfaction among participants with clinical levels of baseline depressive or anxiety symptoms
|
Participants with PHQ-8 baseline score ≥ 10
N= 111
n (%)
|
Participants with GAD-7 baseline score ≥ 10
N= 107
n (%)
|
Sociodemographic Characteristic
|
|
|
Age in years (mean, sd)
|
38 (13.57)
|
37 (12.28)
|
Race/ethnicity
Non-Hispanic Black
Non-Hispanic White
Other
|
37 (33%)
55 (50%)
19 (17%)
|
32 (30%)
56 (52%)
19 (18%)
|
Sex at Birth
Female
Male
|
83 (75%)
28 (25%)
|
81 (76%)
26 (24%)
|
Sexual Orientation
Sexual Minority
Heterosexual
|
19 (17%)
92 (83%)
|
19 (18%)
88 (82%)
|
Education
Graduate or Postgraduate Degree
College Degree
Some College or technical school
High School (Grades 9 - 12)
|
32 (29%)
43 (39%)
21 (19%)
14 (13%)
|
24 (23%)
43 (41%)
22 (21%)
16 (15%)
|
Employment
Full Time Employed
Part Time Employed
Not Employed
Other
|
53 (49%)
11 (10%)
29 (27%)
15 (14%)
|
57 (54%)
9 (9%)
22 (21%)
17 (16%)
|
Marital Status
Divorced/Separated/Widowed
Married/Partnered/cohabiting
Single
|
10 (9%)
50 (47%)
47 (44%)
|
10 (10%)
48 (46%)
47 (45%)
|
Health Insurance
Government Based Insurance
Private Insurance
No Insurance/ Prefer not to answer
|
40 (37%)
46 (43%)
21 (20%)
|
37 (36%)
45 (43%)
22 (21%)
|
Clinical Characteristics
|
Baseline Depressive symptom severity
Minimal
Mild
Moderate
Moderate-severe
Severe
|
0 (0%)
0 (0%)
55 (50%)
30 (27%)
26 (23%)
|
7 (7%)
21 (20%)
25 (23%)
29 (27%)
25 (23%)
|
Baseline Anxiety symptom severity
Minimal
Mild
Moderate
Severe
|
3 (3%)
29 (26%)
37 (33%)
42 (38%)
|
0 (0%)
0 (0%)
60 (56%)
47 (44%)
|
Concurrent Mental Health Treatment*
Any (Concurrent treatment)
None (Woebot only)
|
54 (49%)
57 (51%)
|
57 (53%)
50 (47%)
|
Adherence Metrics
|
App Utilization
Use of WB-LIFE in at least 4 of 8 weeks
|
74 (67%)
|
69 (64%)
|
Per protocol data set
|
71 (64%)
|
63 (59%)
|
GAD-7 = Generalized Anxiety DIsorder-7 item scale; PHQ-8 = Patient Health Questionnaire-8 item scale
* Concurrent mental health treatment = any psychotherapy or psychotropic medication use at any time during the study
“Per protocol” was defined as using WB-LIFE in at least 4 of 8 study weeks and completing end of study PHQ-8 and GAD-7 assessments.
Depressive Symptoms
In the subgroup with clinically elevated depressive symptoms, PHQ-8 scores significantly decreased over the 8-week study period (mean change -7.28, p < .001). In bivariate regression models, the amount of symptom decline did not significantly differ by age, educational level, employment, or baseline level of anxiety symptoms but did significantly differ across several characteristics tested (Table 2). Non-Hispanic Blacks, those who were single, and those with severe levels of baseline depressive symptoms demonstrated significantly greater amounts of decline in depressive symptoms than Non-Hispanic Whites, those who were married/partnered/cohabiting, and those with moderate levels of baseline depressive symptoms, respectively. Females, participants identifying as sexual minorities, those with private or government-based health insurance, those who used the program on at least 4 of the 8 weeks, and those in concurrent mental health treatment demonstrated significantly lower amounts of decline in depressive symptoms than males, participants identifying as heterosexuals, those with no health insurance or who declined to answer the health insurance question, those who used the program on less than 4 of the 8 weeks, and those not in concurrent mental health treatment, respectively. PP analyses largely confirmed the ITT findings (Supplementary Table 1).
After removing race/ethnicity, insurance, and employment from consideration because of multicollinearity, the final multiple regression model indicated significant differences in the amount of decrease in depressive symptoms at Week 8 by sexual orientation, marital status, baseline depressive symptom severity category, and concurrent mental health treatment (Table 3) in the same directions as each bivariate model described above (in addition, divorced individuals had greater amounts of depressive symptom declines as compared with married/partnered, cohabiting).
Table 2. Unadjusted Bivariate Linear Regression Models of Characteristics Associated with change scores from baseline to Week 8 in depressive symptoms among those with clinically elevated levels of baseline depressive symptoms: PHQ-8 ≥ 10
|
PHQ-8: Week 8 Change Scores
|
Characteristics of Interest
|
Estimates
|
95% CI
|
p-value
|
Use of WB-LIFE in at least 4 of 8 weeks
|
2.9
|
0.51, 5.4
|
0.018
|
Age
|
0.03
|
-0.05, 0.12
|
0.4
|
Race/Ethnicity
Non-Hispanic White
|
Reference Level
|
Non-Hispanic Black
|
-6.0
|
-8.3, -3.7
|
<0.001
|
Other
|
0.02
|
-2.8, 2.9
|
>0.9
|
Sex at Birth
Male
|
Reference Level
|
Female
|
2.7
|
0.09, 5.3
|
0.042
|
Sexual Orientation:
Heterosexual
|
Reference Level
|
Sexual Minority
|
5.6
|
2.6, 8.6
|
<0.001
|
Education
High School
|
Reference Level
|
College Degree
|
-1.9
|
-5.6, 1.8
|
0.3
|
Graduate or postgraduate degree
|
-0.68
|
-4.4, 3.1
|
0.7
|
Some college or technical school
|
1.1
|
-3.1, 5.3
|
0.6
|
Employment
Full Time
|
Reference Level
|
Not Employed
|
2.4
|
-0.36, 5.2
|
0.087
|
Other
|
3.1
|
-0.49, 6.8
|
0.089
|
Part Time Employed
|
3.6
|
-0.32, 7.4
|
0.071
|
Marital Status
Married/Partnered/Cohabiting
|
Reference Level
|
Divorced/Separated/Widowed
|
-2.2
|
-6.2, 1.7
|
0.3
|
Single
|
-4.1
|
-6.6, -1.7
|
<0.001
|
Health Insurance:
No Insurance/Prefer not to answer
|
Reference Level
|
Government based Insurance
|
6.9
|
4.2, 9.7
|
<0.001
|
Private Insurance
|
7.5
|
4.8, 10
|
<0.001
|
BL Depressive Symptom Severity
Moderate
|
Reference Level
|
Moderate-Severe
|
-1.1
|
-3.2, 1.0
|
0.3
|
Severe
|
-9.3
|
-12, -7.0
|
<0.001
|
BL Anxiety Symptom Severity
Minimal
|
Reference Level
|
Mild
|
-1.6
|
-9.5, 6.2
|
0.7
|
Moderate
|
-2.1
|
-9.9, 5.7
|
0.6
|
Severe
|
-7.1
|
-15, 0.71
|
0.074
|
Concurrent Mental Health Treatment*
|
3.2
|
0.94, 5.4
|
0.006
|
BL = baseline; PHQ-8 = Patient Health Questionnaire-8 item scale
* Concurrent mental health treatment = any psychotherapy or psychotropic medication use at any time during the study
Table 3. Adjusted Linear Regression Model (Multiple Regression) of change scores from baseline to Week 8 in depressive symptoms among those with clinically elevated levels of baseline depressive symptoms: PHQ-8 ≥ 10
|
PHQ-8: Week 8 Change Scores
|
Characteristics of Interest
|
Estimates
|
95% CI
|
p-value
|
(Intercept)
|
-2.46
|
-10.16 – 5.24
|
0.527
|
Used the app in at least 4 of 8 weeks
|
0.2
|
-1.75 – 2.15
|
0.84
|
Age
|
0.05
|
-0.03 – 0.14
|
0.229
|
Sex at Birth
Male
|
Reference Level
|
Female
|
-0.96
|
-3.24 – 1.32
|
0.405
|
Sexual Orientation
Heterosexual
|
Reference Level
|
Sexual Minority
|
5.71
|
2.88 – 8.54
|
<0.001
|
Education
High School
|
Reference Level
|
College Degree
|
-1.63
|
-4.33 – 1.07
|
0.234
|
Graduate or postgraduate degree
|
-0.24
|
-3.18 – 2.70
|
0.873
|
Some college or technical school
|
0.88
|
-2.26 – 4.01
|
0.58
|
Marital Status
Married/Partnered/Cohabiting
|
Reference Level
|
Divorced/Separated/Widowed
|
-3.86
|
-7.38 – -0.34
|
0.032
|
Single
|
-3.75
|
-5.78 – -1.72
|
<0.001
|
BL Depressive Symptom Severity
Moderate
|
Reference Level
|
Moderate-Severe
|
-0.09
|
-2.44 – 2.25
|
0.937
|
Severe
|
-5.32
|
-8.16 – -2.47
|
<0.001
|
BL Anxiety Symptom Severity
Minimal
|
Reference Level
|
Mild
|
-3.97
|
-10.29 – 2.35
|
0.215
|
Moderate
|
-4.5
|
-11.02 – 2.02
|
0.173
|
Severe
|
-5.59
|
-12.17 – 0.99
|
0.095
|
Concurrent Mental Health Treatment*
|
2.62
|
0.80 – 4.43
|
0.005
|
BL = baseline; PHQ-8 = Patient Health Questionnaire-8 item scale
* Concurrent mental health treatment = any psychotherapy or psychotropic medication use at any time during the study
NOTE: Final models did not consider race/ethnicity, employment, or insurance status because of multicollinearity.
Anxiety Symptoms
Average GAD-7 scores for each subgroup of interest significantly improved over the course of the study. In the subgroup with clinically elevated anxiety symptoms at baseline, GAD-7 scores significantly decreased over the 8-week study period (mean change -7.45, p < .001). The amount of symptom decline did not significantly differ by use of WB-LIFE at least 4 of 8 weeks, age, sex at birth, educational level, or employment, but did significantly differ across several characteristics tested (Table 4). Non-Hispanic Blacks, those who were single, those with severe levels of baseline depressive symptoms, and those with severe levels of anxiety symptoms demonstrated greater amounts of decline in anxiety symptoms than Non-Hispanic Whites, those who were married/partnered/cohabiting, those with minimal levels of baseline depressive symptoms, and those with moderate levels of baseline anxiety symptoms. Participants identifying as sexual minorities, those with private or government-based health insurance, and those in concurrent mental health treatment demonstrated lower amounts of decline in anxiety symptoms than heterosexuals, those with no health insurance or who declined to answer the health insurance question, and those without concurrent mental health treatment, respectively. PPl analyses largely confirmed the full sample findings, with the exception of concurrent mental health treatment reaching marginal significance (p = .052, Supplementary Table 2).
After removing race/ethnicity, employment, and insurance status from consideration due to multicollinearity, the final multiple regression model indicated significant differences in the amount of decrease in anxiety symptoms at Week 8 by sexual orientation, marital status, baseline anxiety symptom severity category, and concurrent mental health treatment (Table 5) in the same direction as those previously described in each bivariate regression model.
Table 4: Unadjusted Bivariate Linear Regression Models of change scores from baseline to Week 8 in anxiety symptoms among those with clinically elevated levels of baseline anxiety symptoms: GAD-7 ≥ 10
|
GAD-7: Week 8 Change Scores
|
Characteristics of Interest
|
Estimates
|
95% CI
|
p-value
|
Use of WB-LIFE in at least 4 of 8 weeks
|
2.2
|
-0.25, 4.7
|
0.077
|
Age
|
0.03
|
-0.07, 0.14
|
0.5
|
Race/Ethnicity
Non-Hispanic White
|
Reference Level
|
Non-Hispanic Black
|
-5.7
|
-08.2, -3.2
|
<0.001
|
Other
|
-0.12
|
-3.0, 2.8
|
>0.9
|
Sex at Birth
Male
|
Reference Level
|
Female
|
1.8
|
-1.0, 4.6
|
0.2
|
Sexual Orientation
Heterosexual
|
Reference Level
|
Sexual Minority
|
3.7
|
0.65, 6.8
|
0.018
|
Education
High School
|
Reference Level
|
College Degree
|
-1.7
|
-5.3, 1.9
|
0.3
|
Graduate or postgraduate degree
|
-1.8
|
-5.7, 2.1
|
0.4
|
Some college or technical school
|
-0.28
|
-4.5, 3.9
|
0.9
|
Employment
Full Time
|
Reference Level
|
Not Employed
|
2.1
|
-1.0, 5.2
|
0.2
|
Other
|
1.2
|
-2.2, 4.7
|
0.5
|
Part Time Employed
|
2.3
|
-2.2, 6.8
|
0.3
|
Marital Status
Married/Partnered/Cohabiting
|
Reference Level
|
Divorced/Separated/Widowed
|
-1.5
|
-5.8, 2.8
|
0.5
|
Single
|
-2.9
|
-5.4, -0.37
|
0.025
|
Health Insurance
No Insurance/Prefer not to answer
|
Reference Level
|
Government based Insurance
|
5.1
|
2.1, 8.0
|
<0.001
|
Private Insurance
|
6.8
|
3.9, 9.6
|
<0.001
|
BL Depressive Symptom Severity
Minimal
|
Reference Level
|
Mild
|
-1.4
|
-6.2, 3.4
|
0.6
|
Moderate
|
-0.71
|
-5.3, 3.9
|
0.8
|
Moderate-Severe
|
-0.12
|
-4.6, 4.4
|
>0.9
|
Severe
|
-7.3
|
-12, -2.7
|
0.002
|
BL Anxiety Symptom Severity
Moderate
|
Reference Level
|
Severe
|
-4.9
|
-7.1, -2.7
|
<0.001
|
Concurrent Mental Health Treatment*
|
3.2
|
0.90, 5.6
|
0.007
|
BL = baseline; GAD-7 = Generalized Anxiety DIsorder-7 item scale
* Concurrent mental health treatment = any psychotherapy or psychotropic medication use at any time during the study
Table 5. Adjusted Linear Regression Model (Multiple Regression) of change scores from baseline to Week 8 in anxiety symptoms among those with clinically elevated levels of baseline anxiety symptoms: GAD-7 ≥ 10
|
GAD-7: Week 8 Change Scores
|
Characteristics of Interest
|
Estimates
|
95% CI
|
p-value
|
(Intercept)
|
-4.68
|
-10.40 – 1.03
|
0.107
|
Used the app in at least 4 of 8 weeks
|
1.26
|
-1.06 – 3.59
|
0.282
|
Age
|
0
|
-0.11 – 0.11
|
0.975
|
Sex at Birth:
Male
|
Reference Level
|
Female
|
-1.76
|
-4.63 – 1.10
|
0.224
|
Sexual Orientation:
Heterosexual
|
Reference Level
|
Sexual Minority
|
4.47
|
1.20 – 7.74
|
0.008
|
Education Level:
High School
|
Reference Level
|
College Degree
|
-1.7
|
-4.79 – 1.39
|
0.278
|
Graduate or postgraduate degree
|
-1.12
|
-4.72 – 2.48
|
0.536
|
Some college or technical school
|
-0.55
|
-4.38 – 3.28
|
0.776
|
Marital Status:
Married/Partnered/Cohabiting
|
Reference Level
|
Divorced/Separated/Widowed
|
-2.85
|
-7.30 – 1.61
|
0.208
|
Single
|
-4.19
|
-6.69 – -1.68
|
0.001
|
BL Anxiety Symptom Severity:
Moderate
|
Reference Level
|
Severe
|
-3.88
|
-6.14 – -1.62
|
0.001
|
Concurrent Mental Health Treatment*
|
3.2
|
0.95 – 5.45
|
0.006
|
BL = baseline; GAD-7 = Generalized Anxiety DIsorder-7 item scale
* Concurrent mental health treatment = any psychotherapy or psychotropic medication use at any time during the study
NOTE: Final models did not consider race/ethnicity, employment, and insurance status due to multicollinearity.
Safety
No study participant reported an AE or serious adverse event (SAE) during the study. Over the course of the study, 127,773 messages were sent by the 256 participants. A subset of 71 participants provided text inputs containing language suggestive of a potential crisis. Of these participants, four confirmed being in a crisis situation and were automatically provided with resources and support as described in the Safety section of the Methods.